东海陆架盆地椒江凹陷月桂峰组湖相烃源岩特征及发育主控因素  

Characteristics and main controlling factors of lacustrine source rocks of Yueguifeng Formation in the Jiaojiang Sag,East China Sea Shelf Basin

作　　者：张彦振 覃军 王雷 常文琪 徐靖琦 ZHANG Yanzhen;QIN Jun;WANG Lei;CHANG Wenqi;XU Jingqi(Shanghai Branch,CNOOC China limited,Shanghai 200335,China)

机构地区：[1]中海石油(中国)有限公司上海分公司,上海200335

出　　处：《海洋地质与第四纪地质》2024年第4期134-144,共11页Marine Geology & Quaternary Geology

基　　金：中国海油“十四五”重大科技项目子课题“丽水-椒江凹陷早降晚抬背景下烃源岩与运汇单元研究”(KJGG2022-0301)。

摘　　要：20世纪90年代在椒江凹陷钻探发现了油气显示,揭示了油气勘探前景,但此后该凹陷研究较少,尤其是烃源岩缺乏系统研究,制约了勘探进程。为了厘清椒江凹陷月桂峰组烃源岩特征及发育模式,为该凹陷下步勘探部署提供依据,本文从梳理月桂峰组构造-沉积背景出发,利用有机岩石学、生物标志化合物、微量元素等地球化学资料分析了烃源岩特征,在此基础上从古生产力、保存条件、沉降速率三方面讨论了月桂峰组有机质富集的控制因素,建立了烃源岩发育模式。研究表明:月桂峰组烃源岩为陆相箕状断陷湖泊背景下发育的暗色泥岩,有机质类型Ⅱ1-Ⅱ2型,有机质丰度按行业标准达到好—很好,纵向上湖扩期烃源岩厚度最大、分布最广、品质最好;优质烃源岩发育受水生生物发育、半封闭的稳定水体-微咸水环境和适中的构造沉降速率共同控制;箕状断陷背景下缓坡带和洼槽带均发育烃源岩,但二者类型和丰度不同,洼槽带发育水生生物贡献为主、偏还原环境下形成的中深湖相优质烃源岩,缓坡带发育陆源高等植物贡献为主、偏氧化环境下形成的滨浅湖相中等烃源岩。In the 1990s,oil and gas were discovered after drilling into the Jiaojiang Sag,East China Sea Shelf Basin,revealing the prospects for oil and gas exploration.However,since then,there has been little research on this sag,especially the lack of systematic research on the source rocks,which hinders the exploration process.To clarify the characteristics and development model of the source rocks of the Yueguifeng Formation in the Jiaojiang Sag and provide the basis for deploying further exploration wells,we summarized the tectonic and sedimentary background of the Yueguifeng Formation,and analyzed the characteristics of the source rock using geochemical data including organic petrology,biomarkers,and trace elements.Based on that,the controlling factors of the enrichment of organic matter in the Yueguifeng Formation were discussed from the aspects of paleo-productivity,preservation conditions,and sedimentation rate,and a model showing the formation of the source rock was established.Results show that the source rocks in the Yueguifeng Formation are dark gray lacustrine mudstone deposited in the continental half-graben,with kerogen type II1-II2,and the abundance of organic matter was rated good to very good in the industry standards.Source rocks deposited during the lake expansion are the thickest and have the widest distribution and the best quality.The development of high-quality source rocks requires abundant algal material,semi-closed stable water under slightly brackish conditions,and a moderate sedimentation rate.Source rocks are developed in both hanging wall and dip slope under the background of a graben shaped fault depression,but the types and abundance of the two are different.The depocenter developed good source rocks of middle-deep lacustrine facies,which was mainly contributed by algal organisms and formed in a relatively reduced environment.In contrast,the dip slope developed medium to shallow lacustrine facies,which was mainly contributed by terrestrial plants and formed in a relatively oxidized environm

关 键 词：湖相烃源岩 主控因素 椒江凹陷 月桂峰组 

分 类 号：P736[天文地球—海洋地质]